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26 ***********************************************************************/
27
28 #ifdef HAVE_CONFIG_H
29 #include "config.h"
30 #endif
31
32 /*
33 * Matrix of resampling methods used:
34 * Fs_out (kHz)
35 * 8 12 16 24 48
36 *
37 * 8 C UF U UF UF
38 * 12 AF C UF U UF
39 * Fs_in (kHz) 16 D AF C UF UF
40 * 24 AF D AF C U
41 * 48 AF AF AF D C
42 *
43 * C -> Copy (no resampling)
44 * D -> Allpass-based 2x downsampling
45 * U -> Allpass-based 2x upsampling
46 * UF -> Allpass-based 2x upsampling followed by FIR interpolation
47 * AF -> AR2 filter followed by FIR interpolation
48 */
49
50 #include "resampler_private.h"
51
52 /* Tables with delay compensation values to equalize total delay for different modes */
53 static const opus_int8 delay_matrix_enc[ 5 ][ 3 ] = {
54 /* in \ out 8 12 16 */
55 /* 8 */ { 6, 0, 3 },
56 /* 12 */ { 0, 7, 3 },
57 /* 16 */ { 0, 1, 10 },
58 /* 24 */ { 0, 2, 6 },
59 /* 48 */ { 18, 10, 12 }
60 };
61
62 static const opus_int8 delay_matrix_dec[ 3 ][ 5 ] = {
63 /* in \ out 8 12 16 24 48 */
64 /* 8 */ { 4, 0, 2, 0, 0 },
65 /* 12 */ { 0, 9, 4, 7, 4 },
66 /* 16 */ { 0, 3, 12, 7, 7 }
67 };
68
69 /* Simple way to make [8000, 12000, 16000, 24000, 48000] to [0, 1, 2, 3, 4] */
70 #define rateID(R) ( ( ( ((R)>>12) - ((R)>16000) ) >> ((R)>24000) ) - 1 )
71
72 #define USE_silk_resampler_copy (0)
73 #define USE_silk_resampler_private_up2_HQ_wrapper (1)
74 #define USE_silk_resampler_private_IIR_FIR (2)
75 #define USE_silk_resampler_private_down_FIR (3)
76
77 /* Initialize/reset the resampler state for a given pair of input/output sampling rates */
silk_resampler_init(silk_resampler_state_struct * S,opus_int32 Fs_Hz_in,opus_int32 Fs_Hz_out,opus_int forEnc)78 opus_int silk_resampler_init(
79 silk_resampler_state_struct *S, /* I/O Resampler state */
80 opus_int32 Fs_Hz_in, /* I Input sampling rate (Hz) */
81 opus_int32 Fs_Hz_out, /* I Output sampling rate (Hz) */
82 opus_int forEnc /* I If 1: encoder; if 0: decoder */
83 )
84 {
85 opus_int up2x;
86
87 /* Clear state */
88 silk_memset( S, 0, sizeof( silk_resampler_state_struct ) );
89
90 /* Input checking */
91 if( forEnc ) {
92 if( ( Fs_Hz_in != 8000 && Fs_Hz_in != 12000 && Fs_Hz_in != 16000 && Fs_Hz_in != 24000 && Fs_Hz_in != 48000 ) ||
93 ( Fs_Hz_out != 8000 && Fs_Hz_out != 12000 && Fs_Hz_out != 16000 ) ) {
94 silk_assert( 0 );
95 return -1;
96 }
97 S->inputDelay = delay_matrix_enc[ rateID( Fs_Hz_in ) ][ rateID( Fs_Hz_out ) ];
98 } else {
99 if( ( Fs_Hz_in != 8000 && Fs_Hz_in != 12000 && Fs_Hz_in != 16000 ) ||
100 ( Fs_Hz_out != 8000 && Fs_Hz_out != 12000 && Fs_Hz_out != 16000 && Fs_Hz_out != 24000 && Fs_Hz_out != 48000 ) ) {
101 silk_assert( 0 );
102 return -1;
103 }
104 S->inputDelay = delay_matrix_dec[ rateID( Fs_Hz_in ) ][ rateID( Fs_Hz_out ) ];
105 }
106
107 S->Fs_in_kHz = silk_DIV32_16( Fs_Hz_in, 1000 );
108 S->Fs_out_kHz = silk_DIV32_16( Fs_Hz_out, 1000 );
109
110 /* Number of samples processed per batch */
111 S->batchSize = S->Fs_in_kHz * RESAMPLER_MAX_BATCH_SIZE_MS;
112
113 /* Find resampler with the right sampling ratio */
114 up2x = 0;
115 if( Fs_Hz_out > Fs_Hz_in ) {
116 /* Upsample */
117 if( Fs_Hz_out == silk_MUL( Fs_Hz_in, 2 ) ) { /* Fs_out : Fs_in = 2 : 1 */
118 /* Special case: directly use 2x upsampler */
119 S->resampler_function = USE_silk_resampler_private_up2_HQ_wrapper;
120 } else {
121 /* Default resampler */
122 S->resampler_function = USE_silk_resampler_private_IIR_FIR;
123 up2x = 1;
124 }
125 } else if ( Fs_Hz_out < Fs_Hz_in ) {
126 /* Downsample */
127 S->resampler_function = USE_silk_resampler_private_down_FIR;
128 if( silk_MUL( Fs_Hz_out, 4 ) == silk_MUL( Fs_Hz_in, 3 ) ) { /* Fs_out : Fs_in = 3 : 4 */
129 S->FIR_Fracs = 3;
130 S->FIR_Order = RESAMPLER_DOWN_ORDER_FIR0;
131 S->Coefs = silk_Resampler_3_4_COEFS;
132 } else if( silk_MUL( Fs_Hz_out, 3 ) == silk_MUL( Fs_Hz_in, 2 ) ) { /* Fs_out : Fs_in = 2 : 3 */
133 S->FIR_Fracs = 2;
134 S->FIR_Order = RESAMPLER_DOWN_ORDER_FIR0;
135 S->Coefs = silk_Resampler_2_3_COEFS;
136 } else if( silk_MUL( Fs_Hz_out, 2 ) == Fs_Hz_in ) { /* Fs_out : Fs_in = 1 : 2 */
137 S->FIR_Fracs = 1;
138 S->FIR_Order = RESAMPLER_DOWN_ORDER_FIR1;
139 S->Coefs = silk_Resampler_1_2_COEFS;
140 } else if( silk_MUL( Fs_Hz_out, 3 ) == Fs_Hz_in ) { /* Fs_out : Fs_in = 1 : 3 */
141 S->FIR_Fracs = 1;
142 S->FIR_Order = RESAMPLER_DOWN_ORDER_FIR2;
143 S->Coefs = silk_Resampler_1_3_COEFS;
144 } else if( silk_MUL( Fs_Hz_out, 4 ) == Fs_Hz_in ) { /* Fs_out : Fs_in = 1 : 4 */
145 S->FIR_Fracs = 1;
146 S->FIR_Order = RESAMPLER_DOWN_ORDER_FIR2;
147 S->Coefs = silk_Resampler_1_4_COEFS;
148 } else if( silk_MUL( Fs_Hz_out, 6 ) == Fs_Hz_in ) { /* Fs_out : Fs_in = 1 : 6 */
149 S->FIR_Fracs = 1;
150 S->FIR_Order = RESAMPLER_DOWN_ORDER_FIR2;
151 S->Coefs = silk_Resampler_1_6_COEFS;
152 } else {
153 /* None available */
154 silk_assert( 0 );
155 return -1;
156 }
157 } else {
158 /* Input and output sampling rates are equal: copy */
159 S->resampler_function = USE_silk_resampler_copy;
160 }
161
162 /* Ratio of input/output samples */
163 S->invRatio_Q16 = silk_LSHIFT32( silk_DIV32( silk_LSHIFT32( Fs_Hz_in, 14 + up2x ), Fs_Hz_out ), 2 );
164 /* Make sure the ratio is rounded up */
165 while( silk_SMULWW( S->invRatio_Q16, Fs_Hz_out ) < silk_LSHIFT32( Fs_Hz_in, up2x ) ) {
166 S->invRatio_Q16++;
167 }
168
169 return 0;
170 }
171
172 /* Resampler: convert from one sampling rate to another */
173 /* Input and output sampling rate are at most 48000 Hz */
silk_resampler(silk_resampler_state_struct * S,opus_int16 out[],const opus_int16 in[],opus_int32 inLen)174 opus_int silk_resampler(
175 silk_resampler_state_struct *S, /* I/O Resampler state */
176 opus_int16 out[], /* O Output signal */
177 const opus_int16 in[], /* I Input signal */
178 opus_int32 inLen /* I Number of input samples */
179 )
180 {
181 opus_int nSamples;
182
183 /* Need at least 1 ms of input data */
184 silk_assert( inLen >= S->Fs_in_kHz );
185 /* Delay can't exceed the 1 ms of buffering */
186 silk_assert( S->inputDelay <= S->Fs_in_kHz );
187
188 nSamples = S->Fs_in_kHz - S->inputDelay;
189
190 /* Copy to delay buffer */
191 silk_memcpy( &S->delayBuf[ S->inputDelay ], in, nSamples * sizeof( opus_int16 ) );
192
193 switch( S->resampler_function ) {
194 case USE_silk_resampler_private_up2_HQ_wrapper:
195 silk_resampler_private_up2_HQ_wrapper( S, out, S->delayBuf, S->Fs_in_kHz );
196 silk_resampler_private_up2_HQ_wrapper( S, &out[ S->Fs_out_kHz ], &in[ nSamples ], inLen - S->Fs_in_kHz );
197 break;
198 case USE_silk_resampler_private_IIR_FIR:
199 silk_resampler_private_IIR_FIR( S, out, S->delayBuf, S->Fs_in_kHz );
200 silk_resampler_private_IIR_FIR( S, &out[ S->Fs_out_kHz ], &in[ nSamples ], inLen - S->Fs_in_kHz );
201 break;
202 case USE_silk_resampler_private_down_FIR:
203 silk_resampler_private_down_FIR( S, out, S->delayBuf, S->Fs_in_kHz );
204 silk_resampler_private_down_FIR( S, &out[ S->Fs_out_kHz ], &in[ nSamples ], inLen - S->Fs_in_kHz );
205 break;
206 default:
207 silk_memcpy( out, S->delayBuf, S->Fs_in_kHz * sizeof( opus_int16 ) );
208 silk_memcpy( &out[ S->Fs_out_kHz ], &in[ nSamples ], ( inLen - S->Fs_in_kHz ) * sizeof( opus_int16 ) );
209 }
210
211 /* Copy to delay buffer */
212 silk_memcpy( S->delayBuf, &in[ inLen - S->inputDelay ], S->inputDelay * sizeof( opus_int16 ) );
213
214 return 0;
215 }
216